Demand within the wireless cellular communications industry has increased such that according to the International Association for the Wireless Telecommunications Industry, the wireless penetration rate in the United States went from 34% of the total U.S. population in 2000, to 93% in June of 2010, while annualized total wireless revenues increased from $68.3 billion in June of 2000, to 255.8 billion in June of 2010. Likewise, annualized total wireless data revenues have increased from $139.4 million in June of 2000, to $46.8 billion in June of 2010. This data overwhelmingly demonstrates that wireless data utilization has escalated substantially, thereby forcing the industry to satisfy ever-increasing demands for speedier services and increasing system capacities.
In typical cellular wireless communication systems, geographic service areas are divided into coverage areas called cells. A cell can be further divided into more defined and compact areas called sectors. The cell and its associated sectors are served by a cellular base transceiver station (hereinafter BTS) which facilitates RF radio frequency communication between the mobile communication devices (cell phones) and the telephone network and/or data network, known as the internet. A typical BTS comprises multiple RF radio transceiver units and antennas that provide bi-directional RF communication links, known as traffic channels, to and from the mobile communication devices. The antennas that are connected to the BTS facilitate the transmission and receipt of the RF signals that pass within a cell or sector. Such antennas are typically positioned outdoors on cellular towers or they may be placed on the tops or sides of buildings; they may even be placed at various strategic locations within the buildings. The BTS radio transceiver hardware and its corresponding capacity is also strategically located in order to maximize cellular communications coverage over large geographical areas and/or to serve a very large number of cellular users. Each BTS is typically connected to a base station controller (hereinafter BSC) which monitors and controls all of the RF activity within its connected network and is further communicatively coupled to the telephone or data network via backhaul connections. A backhaul connection is a form of a signal transport means such as a coaxial cable wiring, a fiber optic cable wiring, or even microwave point-to-point transceivers. With fiber optic backhaul connections, the transmitted RF signal is first modulated into a light signal and then sent through single or multi-mode fiber optic cable. At the far end of the fiber, the optical signal is reconverted to the original RF signal. With microwave point-to-point backhaul connections, the transmitted RF signal is first digitized into a microwave signal which is then transmitted along a connection of radio point-to-point links where the original RF signal has been modulated and/or digitized. The digitized microwave signal is reconverted at the far end to the original RF signal. Microwave or fiber optic backhaul connections can also be used to digitize the RF signal for encapsulation prior to transmitting the signal through the internet. Any transport mechanism that reproduces the original input RF signal at an end point could be considered backhaul transport.
The increased demand for additional cellular capacity has also required that the radio resource channel capacity of each BTS be matched to the cell size profile of the particular cell in which the BTS is located. The current industry method for matching cell capacity is to physically provide each BTS with overly redundant radio channel resources so that peak demands of a network will always be satisfied when those needs arise. However, the cost of the redundant radio transceiver hardware is extremely expensive, as are the costs of maintaining the transceiver hardware. As a means of tempering the need for additional BTS cell coverage, the industry commonly uses RF repeaters in each BTS, also known as “over the air” repeaters, which effectively extend the range of a particular cell's coverage area where the BTS was located.
Another means used in the industry for extending a base transceiver station's coverage area while simultaneously increasing a network's system capacity without resorting to the provision of redundancy has involved the diversification of the antenna systems themselves. One trend has been to avoid the very tall, stand-alone cellular antenna towers for a variety of reasons. One reason is that many cities and municipalities now regulate the height and location of the towers, making their installation an impossibility in some service areas. Another reason is related to the fact that large, stand-alone towers require high power amplifiers to transmit the radiated signal into various geographical areas without compromising the signal. To overcome those problems, a more recent industry trend is to use physically shorter cell towers because they operate at lower power levels, which favorably facilitates RF traffic channel code signal re-use. Another recent industry trend is to utilize multi-tiered towers as a means of fine tuning the coverage area within each cell in accordance with the implementation environment. For example, macro cells are regarded as cells where the base station antenna is installed on a mast or on a building, but above the average roof top level. Micro cells are cells whose base station antenna is installed anywhere where the height of the antenna is under the average roof top level; micro cells are the typical application in urban areas. Another form of a micro cell is that of a distributed antenna system (hereinafter DAS). With a DAS system, a plurality of interconnected antennas are connected to the cell's BTS by the various transport mechanisms that were mentioned above, such as a coaxial cable, fiber optic cable, point-to-point microwave, etc., as a means to extend the BTS coverage area far from the intended originating cell site. Even though a DAS system is typically used in outdoor applications, it is not uncommon to employ a DAS system within the interiors of high-rise office buildings. In this way, the capacity demands that are solely originating from within that particular building can be more readily satisfied without the need for redundant transceiver capacity at the BTS. Of course, some service providers will also dedicate redundant BTS equipment within that office building in addition to employing a DAS system. Another form of fining tuning a coverage area involves the implementation of pico cells, which are small capacity cells whose coverage diameter is a few dozen meters and where the antennas are mainly located inside a building. Thus, it should be appreciated that by using different antenna heights, as well as DAS antenna systems, the capacity needs in a particular service area can be theoretically being met throughout the peak service needs of the day. Although the antenna systems and their utilizations have effectively extended the coverage areas of a BTS, the BTS itself only has a fixed amount of usable RF radio channel resource capacity. As it currently stands, that capacity cannot be transferred or shared between cells to increase the capacity of a BTS associated with a cell or a DAS system. Thus, the current form of allocating traffic capacity in any particular cell is considered static.
Wireless cellular service operators strive to provide the ideal wireless cellular network, where all of their cellular users can readily access the network. This ideal situation presents a common issue to all service providers where, at certain locations and at certain times of the day, many more users are attempting to access the network than at other periods during the day. A prime example is the problem of dealing with rush hour capacity overload. This particular peak time of the day requires more capacity resources along the major transportation routes in order to provide quality service to their commuting users. That additional capacity almost always comes in the form of redundant radio transceiver resources being provided to the BTS that neighbors the transportation routes. Alternatively, at non-peak hours during the day, these redundant RF radio channel resources sit idle. Unfortunately, this idle capacity is in the form of very costly redundant radio transceiver hardware that is physically located onsite in almost all of the network base transceiver stations. Moreover, even if the ideal wireless cellular network is not provided, the users expect an acceptable quality of service (QoS) throughout the entire day. The quality of service, or QoS, is the capability of a cellular service provide to provide what is considered a satisfactory level of service. That expected threshold level of service includes immediate access to the cellular network system, adequate voice quality, consistent signal strength, a very low rate of call blocking, a low rate of dropping probability, and high data rates for multimedia and data applications. System-wide quality of service performance is so important to the various cellular service providers that they employ RF traffic engineers to continuously study these aspects of service quality and generate QoS data reports that relate to a service provider's entire wireless cellular network system. These reports are reviewed daily by the engineers to determine if and when a particular cell or sector is experiencing unacceptable levels of QoS due to insufficient RF radio transceiver hardware capacities within that cell or sector.
The above mentioned shortfalls and the progression of the various means for extending BTS coverage and/or capacity is the result of the evolution of the cellular industry itself. That evolution began with what was known then as the advanced mobile phone system (AMPS). This was an analog radio system that used frequency-division multiple access (FDMA) technology. A major shortfall of this system was that it could only hold one cellular phone call per frequency channel. In short order, that system was later improved with the introduction of the narrow band AMPS (NAMPS). That system increased capacity by using only one third of the AMPS channel width per phone call, which effectively allowed three phone calls within the same AMPS band width. The next major system break through in capacity gains was realized with the introduction of the digital cellular system. That system typically uses some type of phase modulation to send and receive digital signal information rather than analog signal information. Modulation format advancements in all later systems have become increasingly complex in order to get as much capacity out of the available frequency bandwidth as possible. In this early digital system, the first common digital format used by service providers was the time-division-multiple-access, also known by those in the art as TDMA (hereinafter TDMA). TDMA represents an access method for shared medium networks whereby users are allowed to share the same frequency channel by dividing the radio frequency signal into discrete time slots so that the modulated signal within each time slot can be transmitted in rapid succession. This methodology increases system capacity because it allows multiple radio frequency base stations to share the same transmission medium, or radio frequency channel, while using only a part of that station's channel capacity. The TDMA methodology is used in digital 2G cellular systems such as global system for mobile communications (hereinafter GSM), IS-136, personal digital cellular (PDC), and iDEN. Those in the art readily are familiar with each of those TDMA formats, therefore, they will not be further explained. The GSM format was one of the most popular 2G systems and it was actually a hybrid of the TDMA and FDMA technologies. With GSM, a 200 KHz-wide frequency channel is provided so that up to eight cell phone users could use the same frequency channel at the same time. However, the newest TDMA technology which is related to GSM, is currently being phased out of service by all of the major service providers such as Sprint, AT&T, etc., because of new system advances. Furthermore, because of the deceasing use of this format, only a few manufacturers are still supplying transceiver equipment based on that technology. All of the above-mentioned technologies are considered narrow band RF technologies since they rely upon the same basic concept of FM radio.
The next advance over the GSM technology was that known as CDMAOne, which is a 2G CDMA digital air interface standard that operates on a 1.23-1.25 MHz wide channel. CDMA is unlike TDMA or FDMA as this system is entirely a spread-spectrum, code derived, time-dependent system for transmitting information rather than being based on a system that transmits codes within certain timeslots on a designated frequency channel. The Walsh code is the term used for the industry assignment of digital modulation codes that are used for separating individual conversations from control signals on the RF carrier that is transmitted from a CDMAOne (2G) base transceiver station. This code uniquely identifies each of the traffic channels or user conversations. In CDMAOne (2G), the only way to address individual user channels within a transmission is to demodulate the RF wideband spread-spectrum signal and then to detect that channel's individual Walsh codes. The Walsh codes consist of the Pilot, Paging, Sync, and traffic channels. The Pilot channel is always assigned the Walsh code 0, while the Paging channels are found on one or more Walsh codes 1-7. The Sync channel is always assigned Walsh Code 32, while all remaining Walsh codes are assigned to the traffic channels. A PN Offset, also called a Pilot PN, is one of the 512 short code sequences that are used to differentiate between the various sectors that are assigned to a base station transceiver for communication with mobile units.
The CDMAOne (2G) system has now evolved into the more advanced 3G technology, known as CDMA2000, which is the first 3G technology to be deployed. This technology is still based upon a wide band spread-spectrum RF signal that is code-based and time sensitive and it was deployed in three phases: the first being 1xRTT (radio transmission technology), the second being 1xEV-DO (Evolution Data Optimized), and the third being CDMA2000 3x. Each of these phases facilitated even more capacity and faster data rates. The most recent technologies, known as WiMax and Long Term Evolution (LTE), are currently being marketed and are considered 4G technologies. These 4G technologies use Orthogonal Frequency Division Multiplex (OFDM) as their modulation format. As was mentioned above, the modulation schemes of each of these advancing technologies continues to become more and more complex in their attempt at providing even larger capacities and data speeds. Regardless of these improvements, these technologies are very similar to the CDMA format in that they all use wideband spread-spectrum formats and codes, now called symbols, as the basis to arrive at their traffic channels. Furthermore, they are highly time-dependent, which requires the use of global positioning systems (hereinafter GPS) to synchronize the system's transmission times.
As the cellular wireless industry has evolved, several inventive solutions were offered to address the shortfalls that plagued the cellular communications field at that particular time in the field's evolution. For example, in Salmela, U.S. Pat. No. 5,805,996, issued Sep. 8, 1998, a method was proposed for enhancing coverage to specific areas within a cell by adjusting the direction of one or more of its antennas. In this patent, traffic channels from a low-demand cell are steered to a high-demand cell by redirecting the antenna in the high-demand cell towards the low-demand cell. In a limited sense, this additional capacity was provided by the high-demand cell as that cell's BTS capacity was already capable of taking on the additional traffic. However, this patent failed to provide a method of actually transferring BTS capacity to another cell. In Doren, U.S. Pat. No. 5,854,986, issued Dec. 29, 1998, a method was disclosed for coupling a plurality of radio transceivers to low power distributed antennas (DAS). The object of this method was specifically directed towards providing coverage to confined areas with overly high capacity demands and alternatively, to provide coverage to low capacity areas. These confined high and low demand areas typically represent service areas that a normal cell site would not be adequately provide sufficient service coverage. In Doren, the coupling of the BTS equipment capacity is pre-determined statically during installation. Therefore, this method does not offer a dynamic solution towards meeting capacity demand needs which are continuously changing during the course of a day or because of a special event or situation that creates an instant demand for additional capacity, such as when a very large number of cellular users are concentrated into one area because of that event or situation. In Labedz, U.S. Pat. No. 5,852,778, issued Dec. 22, 1998, a method was disclosed using the CDMA technology format whereby cells could expand their coverage into a cell that has coverage area holes that are caused by a malfunctioning radio transmitter in that cell. This method was not founded on fluctuating traffic considerations nor did it solve the problem of providing additional BTS radio channel transceiver capacity to address dynamic coverage demands. In Gilmore, U.S. Pat. No. 5,861,844, issued Jan. 19, 1999, a method was disclosed where a combiner array and an RF switch matrix were used to combine the antenna path of a failed radio transceiver with that of the antenna path of a functioning radio transceiver. The combining of the antenna elements provided temporary radio transceiver coverage until a replacement for the failed unit was installed. Therefore, this method was only concerned with offering a level of reliability that there would be some form of temporary coverage within a cell, but it did not address a way to guarantee that all of the radio channel capacity of the malfunctioning cell would be met by the relied-upon cell. In Rui, U.S. Pat. No. 5,890,067, issued Mar. 30, 1999, a method was disclosed that involved the use of centralized, narrow beam antennas that followed the mobile cellular user. Differing antenna beam widths were employed to provide zones of coverage for low, medium, and high density traffic. In this and in Salmela's invention, the capacity improvements were limited since the radio transceiver capacity was being steered locally within a single cell or sector, very similar to what is known as a smart antenna. Finally, in Schwartz, U.S. Pat. No. 6,594,496, which was issued Jul. 25, 2003, a method was disclosed for re-routing centralized base station RF radio transceiver channel resources to adjacent cells that required additional capacity. Schwartz provided its own form a centralized base station controller that continually monitored and gathered specific information on interconnected base station traffic. Based on that information, the controller would then switch resources to a networked cell in need of additional capacity as long as the resources were not restricted. One shortfall of this patent was that it was designed around the narrow band technologies of analog and possibly TDMA, which was in its early stages at that point of time. As mentioned above, analog technologies are now non-existent and have not been deployed for over a decade, and TDMA technologies are quickly being phased out of service by the major service providers who are now employing the higher capacity technologies such as CDMA. Furthermore, the number of physical RF radio channels that can be grouped together in RF re-use plans are finite, thereby severely limiting the amount of actual transferred capacity that can be realized. Those in the field understand that with today's CDMA-based 3G and 4G technologies, the issues of co-channel, adjacent channel, or neighbor-cell frequency interference are no longer a concern, as it was in Schwartz, since the current technology formats of all service providers use the same frequencies, system wide. Of course, each service provider is assigned a unique frequency band or bands within which his system must be operated. Unlike Schwartz, there is no longer the need to incorporate a frequency plan to manage cell resource allocation and/or sharing since a common frequency is used by all of the base transceiver stations within a cellular network. In addition, each provider may have multiple-wide band frequencies that they control and operate, but those frequencies do not interfere with each other since the current technology formats are based on traffic codes rather than on traffic frequencies which have to be managed and accounted for. Novice RF and system engineers in today's CDMA and CDMA-like technologies fully understand that a base station controller (hereinafter BSC) would require inputting of the specific Walsh codes that are defined for the base transceiver station that is to receive the reallocated resources and for all of the base transceiver stations that neighbor that base transceiver station. The inputting of the Walsh codes would have to take place prior to the reallocation in order to ensure that the added codes are being considered as additional capacity and not code interferers by the BSC and of all of the affected base transceiver stations as being by the reallocation. If these codes were added to the base transceiver stations which now use the most-current technology formats without the BSC first completing the necessary code definition work, the ability of all of the affected base transceiver stations to provide a certain quality of service would be gravely compromised since there would be a significant rise in the signal-to-noise thresholds in the entire RF area served by that BSC. A rise in the signal-to-noise threshold would result in dropped calls, call failures and cause severe call interference. Thus, it should be appreciated that the Schwartz methodology and technology could not be applied to today's CDMA technology or to CDMA-like technology, or to the latest (OFDM) type formats. Otherwise, greater and more serious operational problems would occur when compared to the problem of not having enough radio channel resource capacity in a particular cell. Since Schwartz fails to teach or even mention that certain fundamentals which are related to today's technology formats must be accounted for prior to radio channel resource reallocation, the Schwartz methodology and hardware would not be able to transfer resources to another cell without experiencing severe system degradation. Therefore, Schwartz offers no viable solution for capacity reallocation with the CDMA and CDMA-like technology formats that are universally being used by all major wireless service providers today.
Moreover, Schwartz also fails to address network reallocation time delays, which is another extremely critical aspect that requires consideration with today's technologies. It well known that a time delay will occur when transmitting RF signals or data from one location to another, regardless of the types of backhaul connections within the cellular network. These timing errors usually occur when the signal propagation delay is too long and they must be accounted for within the cellular network in order to prevent call failures on any call handing in or handing out of the cell. Such delays may result for a number of different reasons but the majority of the delays are caused by the number and types of signal conditioners that are utilized within the cellular network. For example, with CDMA2000 (3G), all base transceiver stations must be synchronized within a few microseconds of each other in order for the BTS station identification mechanisms (Walsh codes) to work. Because of these time delay sensitivities, the CDMA2000 network, as well as the WiMax, LTE, and future 4G technologies, all depend upon GPS to maintain a very precise clocking within the cellular network BTS hardware. The GPS time stamp clocking system provides a very precise timing function for synchronization and decoding of the RF modulating technology schemes. In the case of an expected and overly long timing delay, special timing delay codes, known as PN Offset codes, are introduced into the network's BSC as a means to account for the long delays. Sometimes the received PN Offset codes or the timing of the BTS's short codes relative to the system time, may be different from that of the value designated on the Sync channel. When that occurs, a handoff will fail or a call initiation will not be completed. Phones or data devices already using the cell site can remain on the air because they derive their timing from the signals transmitted by the base station. However, phones that are using other cell sites or sectors may be prevented from using an intended target site resource because the cellular devices will be confused by the error in frequency. This error creates what is known in the art as the “island cell” effect. By itself, the network cell is still functional, but to the rest of the system, that cell is inaccessible. In that case, the island cell effect would be caused by timing delays from the addition of the donor RF radio channel resources to the existing resources of the base transceiver station that is being targeted for additional capacity since the donor RF transmission or backhaul retransmission signal would induce too great a time of arrival differential for the user device to use that added RF resource. The only way to avoid the island cell effect is to compensate for the timing delay prior to the reallocation of the resources.
The center piece of the Schwartz patent is its specially designed controller and algorithms, and it is evident that the Schwartz controller was designed for use with an analog and/or TDMA format technology since Schwartz is trying to manage the individual traffic channels as a means to optimize overall system performance. Although managing individual traffic channels may have been possible with the old format technologies like analog and TDMA, that same method is not possible when using current formats such as CDMA or CDMA-like technologies. With the current formats, there is no known way of separating the individual traffic codes from an RF carrier and then uniting those codes at another location since the code's encryptions and decryptions are based on the donor PN short codes, Sync codes, and Long codes. Thus, without the inclusion of those codes, there is no known way to decode the reallocated radio channel resources. In other words, the entire RF resource would have to be switched, including the PN, Sync, and Long codes, as well as the traffic channels, which to date, is not possible. Therefore, those in the field who are familiar with the type of traffic resources being used today would understand that switching those resources from one BTS cell to another would never be possible using the methodologies being taught by Schwartz. This is due to the fact that Schwartz fails to account for the signal-to-noise threshold considerations that are related to the code additions, fails to account for inherent equipment and RF transmission time delays prior to the reallocation of capacity resources to the target BTS, and has basic controller traffic channel management issues. In fact, none of the above-mentioned patents address the need to configure the network BSC with the critical Walsh code and time delay information before making the reallocation of radio channel resources. As previously emphasized, with the presently-used CDMA and CDMA-like technologies, the RF radio channel resources that are being reallocated, require that the timing delays of RF transmission and/or re-transmission of the sector-specific codes have to be accounted for by the BSC prior to putting those codes into service. If not accounted for, code signal-to-noise threshold interference issues will be introduced into the network and the network will experience a severe degradation in the quality of service for the cell receiving the reallocated resources and that cell's neighboring cells.
Therefore, a need currently exists for a system and methodology that can identify when a cell or sector within a cellular wireless communications network needs additional RF radio channel resources to maintain an acceptable quality of service, and which can further identify where idle RF radio channel resources exist and then direct the transfer those resources in batch form to the cell or sector in need.